Several groups of rifamycin derivatives are known, all of which have quite similar structures.
From U.S. Pat. Nos. 4,124,585 and 4,124,586, it is known that 3-aminorifamycin SV can react with aldehydes to give Schiff's bases of 3-aminorifamycin SV itself or cyclic derivatives containing the following partial structure: ##STR2## It was to have been expected that 3-aminorifamycin SV would also react with ketones but this is not so.
However, there is a need for new and improved derivatives of rifamycin and we have, surprisingly, found that 4-piperidinone derivatives react with 3-aminorifamycin S to give new compounds which have remarkable antibacterial properties.